1. Technical Field
The present invention relates to an apparatus for and method of heating an operating fluid, and has particular application in a frying method and a frying apparatus which have high energy efficiency, and low waste heat.
2. Description of Related Art
The present invention has particular application in the manufacture of snack foods, more particularly potato chips.
In many industrial processes there is a need to heat an operating fluid, and there is a general desire to provide energy efficient processes, having minimum carbon footprint, to achieve that heating. For example, frying processes are commonly used to produce a variety of different fried foodstuffs. Frying is particularly used to cook snack food products such as potato chips. In potato chip manufacture, cut slices of raw potato are cooked in a fryer containing cooking oil at an elevated temperature. Energy is required to heat the oil and maintain it at the desired cooking temperature. In addition, the frying process dehydrates the potato slices and a large volume of steam is generated which is typically captured by a hood disposed over the fryer and exhausted to the atmosphere, or the steam is passed into a thermal oxidiser for volatile destruction.
There is a generally recognised desire in the snack food manufacturing art to reduce the energy costs and waste heat generation of the frying apparatus. However, it is also necessary to ensure that the frying process and apparatus still produce a high quality product to the consumer which meets customer acceptance and is reliably and consistently achievable despite high production volumes. In particular, potato chips are normally required to meet very strict customer acceptance criteria for the respective product, for example having specific moisture and oil-in-chip contents, and the desired taste, organoleptic and other sensory attributes.